Beyond simple geofencing (which just logs an alarm), construction sites are adopting "active virtual fencing" on bulldozers and graders. The system links the GPS/GNSS receiver to the ECU. If the machine approaches a pre-programmed boundary-such as a protected wetland, a buried high-pressure gas line, or a blast exclusion zone-the system intervenes physically.
At 10 feet from the boundary, the operator gets a visual warning on the screen and an audible chime. At 5 feet, the machine slows down to a crawl, reducing the throttle limit and the pump flow regardless of the operator's pedal input. If the operator ignores this and attempts to cross the line, the system will actually brake the machine to a stop and prevent the hydraulics from operating in that direction.
While this prevents catastrophic utility strikes, it creates a dangerous situation if the boundary is input incorrectly or if the GPS drifts in a "multipath" environment (near tall buildings or rock faces). Operators have been stuck in "dead zones" where the fence is mis-placed, unable to move the machine to safety or continue work without a technician password to override the GPS lock.
